(1) Field of the Invention
The invention relates to the use of low dielectric constant materials in the fabrication of integrated circuits, and more particularly, to a method of improving adhesion of low dielectric constant materials to overlying materials in the manufacture of integrated circuits.
(2) Description of the Prior Art
Low dielectric constant materials, having a dielectric constant (k) of less than about 3.1, are preferably used in the fabrication of integrated circuits to reduce capacitance. An integration challenge facing processes incorporating low dielectric constant materials is the adhesion of these low dielectric constant materials to overlying layers. Poor adhesion is a cause for reliability concerns. A plasma treatment can be used on a low-k dielectric material layer to improve its adhesion property. It is necessary to prevent or minimize damage to the low-k material caused by the plasma treatment.
U.S. Pat. No. 6,346,489 to Cohen et al discloses a method to remove native oxide within a via opening by treating the substrate with a hydrogen-helium plasma. Cohen et al reveal that this treatment does not adversely effect the dielectric constant of a low-k layer through which the opening is made and also that the treatment improves damage made to the low-k layer by oxygen ashing. No mention is made of adhesion concerns of the low-k layer. U.S. Pat. No. 5,998,229 to Lyu et al describes repairing etching damage to an amorphous silicon layer by using a hydrogen or helium plasma treatment. U.S. Pat. No. 6,570,256 to Conti et al shows a method of forming a carbon-graded layer for improving adhesion of low-k dielectrics to the underlying substrate. A helium and/or oxygen treatment is disclosed as an additional or alternative treatment of the substrate to improve adhesion of the substrate. U.S. Pat. No. 6,465,372 to Xia et al includes densification of a low-k film using a plasma treatment. This has nothing to do with adhesion. Furthermore, this patent teaches adhesion enhancement by treating the film in a reducing environment of ammonia.